"While Btrfs is still under heavy development (though it has
been in the mainline kernel for nearly a year) and it still has
room for performance improvements, it does have a nice set of
features like online volume growth, online defragmentation,
transparent compression support, SSD optimizations, and
copy-on-write snapshot support.
"Chris Ball and Josef Bacik are looking to leverage the Btrfs
snapshots support in Fedora 13 by introducing support for system
rollbacks. Under their proposal, a yum plug-in would create a Btrfs
snapshot before every yum transaction. Users could also create
their own Btrfs snapshot at anytime."